Continuously Variable Transmissions (CVTs) have been known for some time. For automotive applications the prior art has primarily used completely mechanical means to achieve variable ratio transmissions. As shown in U.S. Pat. Nos. 4,548,100 and 4,630,504 conical-disc band mechanisms or variators (sliding belts) have been employed with limited success. Conventional mechanical variable ratio transmission designs suffer from the “point contact” problem—to achieve the variable gear ratio the torque is coupled through a very highly loaded small contact area or “point”—with attendant slippage and friction in the process. This problem exists in almost all completely mechanical non-geared designs. The result is increasingly high wear rates as the power capacity of the transmission increases as well as reduced efficiency. This typically results in marginally acceptable wear rates and lowered efficiency in moderate H.P. applications (125H.P.) and very short life or complete failure to function in high H.P. applications over 250H.P.
The prior art showing magnetically coupled transmissions such as U.S. Pat. Nos. 4,616,519 and 2,548,373 are either not true CVT's and or have serious problems generating the high torque levels suitable for automotive applications. Hybrid mechanical/magnetic CVT's have been show that address the slippage problems but usually require exotic magnetic fluids or have problems reliably actuating the electro-magnets.